Method and apparatus from transmitting augmentation panel components on one channel of a two channel wide aspect ratio television signal transmission system

ABSTRACT

Each line of a wide aspect ratio television signal is divided into a main panel component and two augmentation panel components for transmission or storage. The two augmentation panels are transmitted in a multiplex analog format on the same channel. They are transmitted adjacent to one another so that additional signals such as audio signals will occupy the same time slots regardless of the respective widths of the panels. (The sum of the panel widths remains constant even in pan and scan operations). Weighted transition augmentation samples effect a transition from the last redundant pixel of one augmentation panel component to the first redundant pixel of the second augmentation panel component.

CROSS-REFERENCE TO RELATED APPLICATIONS

"Decomposition and Recombination of a Wide Aspect Ratio Image" by thesame inventors, assigned to the same assignee and filed simultaneouslyherewith.

FIELD OF THE INVENTION

The present invention relates to television transmission and receptionand, in particular, high definition television wherein a wide-aspectratio television signal is generated at the transmitting end and thissignal is decomposed into a main panel component adapted to be receivedon a standard NTSC receiver, and one or more augmentation panelcomponents. For reception as a high definition television signal with awide-aspect ratio, the two or more panels must be recombined at thereceiver.

BACKGROUND OF THE INVENTION

A number of U.S. patents have issued describing compatible highdefinition television systems. However, none of these patents teaches amethod or apparatus for generating the main and augmentation panels atthe transmitter and recombining this information at the receiver.

Also known is a paper called "Edge Stitching of a Wide-Aspect Ratio HDTVImage" by J. L. Lo Cicero, M. Pazarci and T. S. Rzeszewski. While thisgives mathematical analyses of the problem, no practical implementationis taught.

SUMMARY OF THE INVENTION

The way in which a wide aspect ratio display is divided into severalpanels at the transmitter and the way in which the recombination ofthese panels takes place at the receiver is crucial in determining thequality of the display. Even when the luminance and chrominance signalsgenerating the main panel and augmentation panel displays are properlyaligned in gain, time, and phase at the receiver, a clearly visiblevertical line with dot crawl would be created at each panel-to-paneljunction. Such an artifact would render the display unacceptable to aviewer.

It is an object of the present invention to furnish a method and systemof decomposing a wide-aspect ratio image into a main panel and at leastone augmentation panel for transmission or recording, and recombiningthe panels at a receiving so that a viewer cannot see any indication ofthe "stitching" between the panels.

In accordance with the present invention, the plurality of horizontalline signals which together constitute a wide aspect ratio televisiondisplay are each considered to have a main panel component having afirst main panel end and a second main panel end, and at least oneaugmentation panel component having a first augmentation panel endadjacent the second main panel end, and a second augmentation panel end.At the transmitter, there is extracted from each horizontal line signala first extracted signal which includes the main panel component, aplurality of main panel redundant samples (pixel values) extending fromthe second main panel end into the augmentation panel component, and amultiplicity of main panel transition samples which are weighted samplesextending from the redundant main panel samples towards the secondaugmentation panel end and forming a transition from full main panelcomponent value to a second value such as, e.g., zero.

Similarly, a second signal includes the augmentation panel component,redundant augmentation panel samples and transition samples. At thereceiver, the augmentation and main panel components are recombined bydeleting the transition samples and weighting the redundant samples ofthe two panels to effect a smooth transition.

When the second signal includes two augmentation panel components, thenumber of transition samples can be substantially decreased bytransmitting the first augmentation panel component immediately followedby the second augmentation panel component. The transition samples needthen only effect a transition from the last sample of the firstaugmentation panel component to the first sample of the secondaugmentation panel component, rather than having to effect twotransitions both down to a reference level.

The objects and features of the present invention will be clearlyunderstood upon consideration of the following detailed description,when read in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 illustrates a wide-aspect ratio image at the source, withextracted 4:3 main panel and two augmentation panels;

FIG. 2 illustrates a staircase luminance variation at the source and theresulting main and augmentation panels;

FIG. 3 is a block diagram of apparatus for main panel/augmentation panelseparation and recombination in accordance with the present invention;

FIG. 4a illustrates gating signals for decomposing a wide aspect ratiopicture into a 4:3 panel and two side panels without overlap;

FIG. 4b illustrates gating signals as in FIG. 4a, but with X-1overlapping redundant samples at each stitch point;

FIG. 5 is a block diagram for the enabling signals required in thesignal extracting apparatus of FIG. 6;

FIG. 6 is a schematic diagram illustrating the panel extractionapparatus according to the present invention;

FIG. 7 illustrates the transmitted and received video envelopes and thegating signals according to the present invention;

FIG. 8 illustrates graphically the main panel-augmentation panel stitchwith a five sample overlap for linear recombination decoder gating; and

FIG. 9 is a block diagram of the receiver apparatus according to thepresent invention;

FIG. 10 is a block diagram illustrating apparatus for varying the stitchpoint location on a line-by-line basis;

FIG. 11a illustrates the line format on an augmentation channel of a twochannel system before fading; and

FIG. 11b is a block diagram for time multiplexed transmission of twoaugmentation panel components on one channel.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be described with respect to the embodimentshown basically in FIG. 1. Here, the output of a television camera or atelecine source has an aspect ratio of 5 1/3:3. For purposes of thisexample, the main panel is a center panel compatible with, and suitablefor, reception on NTSC television receivers currently in service. Thismain center panel is flanked on each side by an augmentation panel,denoted by panel left and panel right, respectively. It should be notedthat the present invention is entirely applicable to any situationwherein a given signal is divided into two or more panels, the panelsthen having to be recombined to yield a desired output display. Theembodiment discussed here, wherein a center panel video signal isflanked by two side panels of equal width, is therefore to be consideredillustrative only.

For further purposes of illustration, FIG. 2 shows a luma staircaseexample for one line of the television signal. FIG. 2a illustrates the 51/3:3 source which is divided into a center panel including most, butnot all, of steps 2 and 7 at its respective extremities, and two sidepanels including, for the left panel, step 1 and part of step 2 and, forthe right hand panel, part of step 7 and step 8.

As illustrated in the block diagram of FIG. 3, in the present preferredembodiment the wide aspect ratio source is subjected to luma/chromaseparation, the luminance signal Y and the chrominance signals I, Qbeing applied to a center/panel separator stage 10. At the output ofseparator stage 10 there are thus two sets of luminance/chrominancesignals, namely the luminance signal (Y) and chrominance signals (I, Q)associated with the center panel, and the luminance and chrominancesignals associated with the side panels. The six signal packets are thenpassed through an edge shaper 12 and processed for transmission in amodulation stage 14 as is well known for NTSC transmission, ortransmission in another standard as appropriate.

In a receiver stage 16, the individually received center and side panelsignals are subjected to NTSC demodulation. The luminance signal is thenapplied to a luminance center/panel stitch stage 18, while thechrominance signals are applied to a similar stage 20. The resultingcombined luminance and combined chrominance signals are then ready fordisplay on a wide aspect ratio receiver.

Two ways of timing gating signals for use in separator stage 10, i.e.for decomposing a wide aspect ratio picture into a 4:3 aspect ratiopicture and two side panels are illustrated in FIG. 4. In both FIG. 4aand FIG. 4b, the wide aspect ratio width is assumed to include Msampling points (pixels). In FIG. 4a these M pixels are divided into Ncenter panel pixels and, on each side 1/2×(M-N) side panel pixels. Thistype of gating results in separation of the panels without overlap. Asimple implementation of a suitable gating circuit is illustrated inFIG. 5a and will be discussed in connection therewith below. On theother hand, in FIG. 4b, the timing of gating signals for accomplishingseparation with overlap are illustrated. Here, the M pixels of a lineare divided into center panel pixels which include the actual centerpanel pixels N and X/2 pixels on each side of the N pixels, i.e. a totalof X redundant pixel samples. Similarly, the panel gating signal extendseach panel by X/2 redundant panel pixels into the area of the N centerpanel pixels. Thus, in each line the separation of the center panel fromthe two side panels creates X-1 overlapping redundant samples at each ofthe two separation or "stitch" points.

FIG. 5 shows simple implementations of circuits for generating thegating signals illustrated in FIGS. 4a and 4b. A counter 50 counts clockpulses from the system clock and is reset by the horizontalsynchronization signals of the video signal. The output signals fromcounter 50 are applied to a decoder 52. Decoder 52 furnishes the outputsP_(L), C, and P_(R), respectively. The first output is P_(L), that isthe left panel enable signal, active from pixel number 1 to pixel number128. Next, center panel enable signal C for separating the center panelis activated. Finally, after the pixel equal to N+1/2 (M-N), namelypixel 800, the signal P_(R) is activated and remains active until theend of the line.

The circuit of FIG. 5 can also represent the circuit necessary toimplement the signal output illustrated in FIG. 4b. The only differenceis that the signal P_(L), which still starts at pixel 1, continues notto pixel 128, but to pixel 133. At the same time, signal C starts not atpixel 128 as above, but instead, at pixel 123, so that signals P_(L) andC are active simultaneously over a range of 11 pixels. One of thesepixels must be carried by one signal anyway, and is not consideredredundant. The same is true at the right-hand side. The signal P_(R)starts prior to cessation of the signal C, while the signal C continuespast the former cut-off, for an additional period of 5 pixels. There isthus, both at the right-hand and at the left-hand side, an overlap ofX-1=10 pixels.

Due to bandwidth limitations, a roll-off, that is a more gradual riseand fall for the center panel and for the side panels is required. Acosine curve implemented as illustrated in FIG. 6 may be utilized forthis purpose. It should be noted that the roll-offs take place outsideof the above-described overlap range, i.e. beyond pixel 133, e.g. forpixels 134-138 for the left panel; 118-122 for the left side of thecenter panel, etc.

Referring now to FIG. 6, the signals P_(L) and P_(R) are applied to theenable input of a programmable read-only memory 60 which is the memoryfor the panels. This PROM is thus enabled for either P_(L) or P_(R).During the time that the PROM 60 is enabled, the addresses read-out fromcounter 50 cause the proper multiplication factors for generating theleft panel component including overlap and cosine roll-off to appear onoutput lines 62 of PROM 60. This multiplication factor is then appliedto the incoming luminance signal by a multiplier 64. Similarly, thesignal C at the output of decoder 52 is applied to enable a PROM 66which is the PROM storing the relevant addresses for the center panel.Again, the output of counter 50 addresses PROM 66 and the values readout from the addresses appear on output lines 68. These multiply thesampled value of the luminance signal in a multiplier 70, the resultantsignals constituting the center panel signals with appropriate overlapand roll-off (herein also referred to as first extracted signals). WhileFIG. 6 illustrates the shaping of the cosine curve for the luminancesignal, the process for the chrominance signals is identical and willtherefore not be described herein. It is also possible to use the samemethod and apparatus for generating center and augmentation panelsignals for baseband video, rather than for luminance and chrominanceseparately.

The signals at the outputs of multipliers 64 and 70 are thus the signalsdenoted as the center and side panel signals for the luminance signal Yat the output of edge shaper 12 in FIG. 3. These signals, along with thecorresponding chrominance signals at corresponding outputs ofcorresponding stages for the I and Q components, are then transmitted,after suitable modulation in modulator stage 14.

The transmitted signals are received at a demodulator 16. With theexception of the "panel fade" input discussed below, the actualmodulation and demodulation are not part of the present invention, arewell known, and will therefore not be discussed in detail. It issufficient to say that the output of demodulator stage 16 consists ofthree sets of signals, namely the Y signals for the center and sidepanels and the I, Q center and side panel signals. The waveshape for,for example, the Y signal is illustrated in FIG. 7c for the center paneland FIG. 7d for the side panels. It will be noted that due totransmission and reception, some ringing in the form of oscillations iscreated at each inflection point, in spite of the cosine roll-off.However, in accordance with the present invention, these oscillations donot form part of the display; i.e. they are gated out at the receiver.

A preferred linear combination gating scheme at the receiver isillustrated in FIG. 8.

Specifically, FIG. 8 illustrates an example of linear weighting for aleft panel-center panel stitch with five sample overlap. The top lineshows the luminance variation in the left panel, while the bottom lineindicates the luminance variation for the center panel. Pixel samples 1,2, 3, 4 and 5 in the left panel are adjacent to the stitch proper whichincludes pixel 6, 7, 8, 9 and 10. It will be noted that the transitionfrom left to center panel commences with pixel 6. Therefore the initialringing of the center signal transition does not affect the finaldisplay at all. The linear transition commences at pixels 6, but isstill 100% weighted for the left panel. Pixels 7 are weighted 75% leftpanel, 25% center panel; pixels 8 at 50--50, pixels 9, 25% left panel75% center panel, while at pixel 10 the transition is complete, i.e. thepanel coefficient weight becomes 0 while the center coefficient weightis 100%.

A circuit similar to the circuit of FIG. 5 in combination with thecircuit of FIG. 9 is used to implement the above described weighting.P_(L), P_(R), C will be generated as illustrated in FIG. 5 and describedwith reference to the transmitter Signals P_(L) and P_(R) are applied tothe enable input of a PROM 90 which has a plurality of address linesconnected to the output of a counter 91 reset, as was counter 50, by thereceived horizontal sync signals. (If the right and left panel signalsare transmitted on a separate channel from the center panel signals, thevideo from both channels is applied to a time base corrector. The H syncsignal is then available at the time base corrector output.) Similarly,signal C is applied to the enable input of a PROM 92, also havingaddress lines connected to the output of counter 91. PROMS 90 and 92hold the weighting factors associated with the side panels and thecenter panel, respectively, including the weighting factors associatedwith the redundant pixels as described above. The outputs of PROMS 90and 92 are applied, respectively, to multipliers 94 and 96 whose secondinputs receive the signals received on the second and first channel,respectively. The outputs of multipliers 94 and 96 constitute,respectively, the left and right panel signals with redundant samplessuitably weighted for transition with the center panel signal at each ofits ends, and the center signal with suitably weighted redundant samplesat each end. The two signals are applied to respective inputs of anadder 98 at whose output appear signals suitable for display on a wideaspect ratio monitor.

The above description illustrates the decomposition and recombination ofthe wide aspect ratio signal on a single line, it being assumed that thestitching locations will be the same on all lines. The visual effect ofthe stitch can be decreased even further if the stitch location isvaried somewhat from line to line, from frame to frame, or in accordancewith ny other convenient plan. For a line by line variation, the circuitof FIG. 10 may be used. There the address signals generated at thereceiver are applied to one input of an adder 101. The second input ofadder 101 is connected to the output of a random number generator 104which is activated by the horizontal synchronization pulses. The outputsof the adder 101, when used to address PROMS 90 and 92 of FIG. 9, causea variation in the start and end of the stitch intervals in a line,within the limits of the numbers within random number generator 104. Therange of numbers in random number generator 104 may, for example, be ±2.

Alternatively, random number generator 104 can be reactivated twice perline, resulting in a slight shift of the left stitch point relative tothe right stitch point.

The enabling signals P_(L), P_(R) and C must either be delayed undercontrol of the random number generator (delay units 106 and 108) or therange of pixels covered by each expanded to include all possibleaddresses given the range of random numbers.

It is also possible to omit the enabling signals entirely, if PROMS 90and 92 store zero as a multiplication factor for all respectiveinapplicable addresses.

Finally, there is a preferred method for transmitting the left panelsignals and the right panel signals on the second channel, if a twochannel transmission system with multiplexed analog transmission isused. The most obvious way of arranging the sequence of signals in eachline of the second channel would be as scanned, namely, the horizontalsynchronizing signal, followed by the color burst, which is followed bythe NTSC modulated left panel signal. The left panel signal is followedby, for example, audio signals, line differential signals forreconstructing the lines not transmitted in the first channel, and,finally, the right panel signal. This arrangement has the disadvantagethat, for a pan and scan system, the respective widths of the left paneland of the right panel may change although the total side panel widthwill remain constant. Such changes would be difficult to carry out withthis arrangement and are much simplified by transmitting the left panelsignals immediately followed by the right panel signals, followed by theaudio and line differential signals. Since changes in the width of theindividual panels then do not affect the total panel width, both theaudio and line difference signals would be in the same position in eachline for any position of the center panel relative to the left and rightpanels.

Additional advantages are to be gained by the positioning of the rightpanel signals next to the left panel signals. As explained withreference to FIG. 8, the redundancy technique used at the receivercauses the right transition of the left panel and the left transition ofthe right panel to be discarded. Instead of rolling off the right partof the left panel signal and the left part of the right panel signal tozero at the transmitter, a linear fade (interpolation) from the lastutilized sample of the left panel to the first utilized sample of theright panel may be used. This fade will also decrease the chance ofringing noted in FIG. 7d. Additionally, the fade may be accomplished ina shorter time than the roll-off in the two directions. The time savedcan be utilized for carrying additional signals.

The circuits illustrated in FIGS. 11a and 11b can be used to accomplishthis linear fade. The same circuit can be utilized whether the incomingsignal is the luminance signal, one of the chrominance signals, or thecomposite television signal. In FIG. 11a it is assumed that the incomingsignal is the second channel (side panel) luminance signal. Thecomponents of this signal, as scanned, are applied to a memory 120, forrepositioning on the line. Insofar as the present invention isconcerned, the output of memory 120 consists of, in each horizontalline, the transition samples at the rising edge of the left hand panel,the left hand panel itself, the redundant samples associated with theleft hand panel, a transition gap of, for example, three samples, theredundant samples associated with the right hand panel, the right handpanel as such, and the transition samples at the trailing edge of theright hand panel. The additional signals, which will be positioned atpredetermined time slots on the remainder of the lines, are notillustrated since they are not relevant to the present invention.

The repositioned signal is applied to the circuit illustrated in FIG.11b. This has an input terminal 121. A latch 124, timed by the trailingedge of P_(L), extracts the last valid sample (redundant sample) l_(o)from the incoming signal. A latch 126 set by the same edge after a delaycorresponding to the number of pixels between l_(o) and r_(o) extractsthe first valid (redundant) sample r_(o) from the right panel (see alsoFIG. 11a). A PROM fader, 128, operating in the same manner as the PROM66 in FIG. 6, furnishes multiplying factors. These are applied toSimilarly, a PROM fader 130, operating as does PROM 66 in FIG. 6,supplies multiplication factors for the left panel sample extracted bylatch 126. These multiplication factors are applied to one input of amultiplying unit 134 whose other input is the above-mentioned sample.The weighted signals from multiplier 132 are applied to one input of anadder 136 whose second input receives the weighted samples frommultiplier 134. The transition signals from adder 136, representing thefade from l_(o) to r.sub. o, are applied to a multiplexer 138.Multiplexer 138 also receives the remainder of the second channelsignals following a delay 140. Delay 140 is a delay corresponding todelay 129, plus any additional delay required to equalize processingtime. Multiplexer 138 provides the appropriate gating between the twosignals at its inputs. The output of the multiplexer 138 is thus thesecond channel signal ready for transmission.

At the receiver, the signal received on the second channel is applied toa memory (not shown). Readout from the memory takes place so that theaugmentation and main channels are restored to their originalrelationship, i.e. the second augmentation panel component is followedby the main panel component which in turn is followed by the firstaugmentation panel component. Any additional signals such as audiosignals and line difference signals follow in whatever empty slots maybe on the line.

Although the system has been described in reference to a preferredembodiment, it should be noted that, throughout, chrominance signalscould be substituted for the luminance signal, and even compositetelevision signals can be used. Further, this system has been shown asembodied in certain hardware. Many variations of such hardware will beevident to one skilled in the art. Further, in many cases software canbe substituted for the hardware in an obvious manner. Finally, althoughthe system is discussed with reference to a two channel transmission,the invention is clearly applicable when transmission of the centerpanel and the side panels is accomplished in one channel.

All of the above embodiments are therefore to be encompassed in thefollowing claims.

We claim:
 1. A system for encoding a television signal comprising a plurality of horizontal line signals together constituting a wide aspect ratio display, into at least one time multiplexed television signal, each of said horizontal line signals having a main component, first and second panel components, and additional signals, said system comprising:(a) means for shaping adjacent edges of said main component and said first and second panel components, wherein said shaping means comprises means for generating at lest one transition sample, said generating means comprising first and second latch means for extracting a last sample of said first panel component and a first sample of said second panel component, multiplier means connected to said first and second latch means, for multiplying said first sample and said last sample by respective predetermined constants, and adder means for adding the multiplied first and last samples; (b) means coupled to said shaping means for disposing said first and second panel components adjacent to one another in time as part of said time multiplexed television signal; and (c) means for incorporating said additional signals as part of said time multiplexed television signal.
 2. A system as set forth in claim 1, wherein:said first panel component includes a plurality of redundant first panel pixels extending from a first panel toward a second panel, and said second panel component includes a plurality of second panel redundant pixels extending from said second panel towards said first panel, and wherein said last sample of said first panel component is a last redundant sample of said component, and said first sample of said second panel component is a first redundant sample of said second panel component.
 3. A system as set forth in claim 1 wherein said time multiplexed television is used for generating a main channel signal comprising said main component.
 4. A system as claimed in claim 3, further comprising:(a) receiving means for receiving said main channel signal and said time multiplexed television signal and for extracting said first and second panel components from said time multiplexed television signal and said main component from said main channel signal; and (b) repositioning means connected to said receiving means for repositioning said first and second panel components and said main component so that said main component occurs in time between said first panel component and said second panel components.
 5. Means for decoding the time multiplexed television signal described in claim 1, comprising:(a) receiving means for receiving said time multiplexed television signal and for extracting said first and second panel components and said main component from said time multiplexed television signal; and (b) repositioning means connected to said receiving means for repositioning said first and second panel components and said main component so that said main component occurs in time between said first panel component and said second panel component.
 6. The receiver as claimed in claim 5 further comprising stitching means connecting to said repositioning means for stitching said main component to said first and second panel components.
 7. A system for transmitting a plurality of horizontal line signals constituting a wide aspect ratio display to a receiving location through a first and second channel, each of said horizontal line signals having a main component transmitted through said first channel and first and second panel components transmitted through said second channel, said horizontal line signal further comprising additional signals including at least one audio signal, one line difference signal, and one synchronization signal transmitted on said second channel, said system comprising:(a) means for applying said first and second components to said second channel adjacent one another in time to create a predetermined part of each of a plurality of second channel horizontal line signals; (b) means for applying said additional signals to said second channel, whereby said additional signals occupy the same time slots in each of said horizontal line signals independent of the individual widths of said first and second panel components; (c) means for generating at least one transition sample bridging said first and second panel components, wherein said at least one transition sample together with said first and second panel components create said predetermined part of each of said plurality of second channel horizontal line signals and wherein said first panel component has a last sample and said second panel component has a first sample following said last sample and said at least one transition sample is immediately adjacent both said last sample and said first sample; and wherein said means for generating said at least one transition sample comprises first and second latch means which extract said last sample of said first panel component and said first sample of said second panel component; (d) multiplier means connected to said first and second latch means for multiplying said first sample and said last sample by respective predetermined constants; (e) delay means coupled to said first and second latch means, for furnishing delayed second channel horizontal line signals; (f) adder means for adding the multiplied first and second last samples thereby creating said at least one transition sample; and (g) multiplexer means for furnishing a multiplexer output signal comprising said delayed second channel horizontal line signals and an output signal from said adder.
 8. A system as set forth in claim 7, further comprising:a signal selector, wherein said multiplexer means has a control input, a first signal input receiving said delayed second channel horizontal line signals and a third input receiving said output signal of said adder, and wherein said selector is at said control input and switches from said first signal multiplexer input to said multiplexer third input following said last sample of said first panel component and prior to said first sample of said second panel component.
 9. A system as set forth in claim 7, wherein:said first panel component includes a plurality of redundant first panel pixels extending from a first panel toward a second augmentation panel, and said second panel component includes a plurality of second panel redundant pixels extending from said second panel towards said first panel, and wherein said last sample of said first panel component is a last redundant sample of said first component, and said first sample of said second panel component is a first redundant sample of said second panel component.
 10. A system as set forth in claim 7, further comprising:receiving means for receiving said main component and said second channel horizontal line signals and extracting said first and second panel components from said second channel horizontal line signals; and repositioning means connected to said receiving means for repositioning said first and second panel components and said main component so that said main component occurs in time between said first panel component and said second panel component.
 11. A system as set forth in claim 7, further comprising means connected to said repositioning means for stitching said main component to said first and second panel component.
 12. A system as set forth in claim 7, further comprising:receiving means for receiving said main component and said second channel horizontal line signals and extracting said first and second panel components from said second channel horizontal line signals; and repositioning means connected to said receiving means for repositioning said first and second panel components and said main components so that said main component occurs in time between said first panel component and said second panel component.
 13. A system as set forth in claim 12, further comprising means connected to said repositioning means for stitching said main component to said first and second panel components. 